This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application entitled AIR CONDITIONER HAVING PRESSURE CONTROLLING UNIT AND ITS CONTROL METHOD filed with the Korean Industrial Property Office on Dec. 18, 2000 and there duly assigned Ser. No. 2000-77926.
1. Field of the Invention
The present invention relates generally to air conditioner, and more particularly to an air conditioner with a pressure regulation device and method for controlling the same.
2. Description of the Prior Art
An air conditioner generates cool air using a refrigeration cycle, and supplies it into a room.
The refrigeration cycle employed in the air conditioner is comprised of a compressor, a condenser, a capillary tube and an evaporator. Gaseous refrigerant sucked into the compressor is compressed into high-temperature, high-pressure gaseous refrigerant by the operation of a motor within the compressor. The compressed gaseous refrigerant discharged from the compressor is condensed (liquefied) to high-pressure liquid refrigerant by heat exchange with outdoor air supplied by a condenser fan. The condensed refrigerant in the condenser is expanded while passing through the capillary tube. The expended refrigerant is evaporated by heat exchange with indoor air, by which process the refrigerant absorbs heat from the surroundings.
FIG. 1 is a schematic diagram showing the construction of the outdoor unit of a conventional air conditioner.
Referring to drawing, the conventional outdoor unit includes a first compressor 1a and a second compressor 1b that are operated at constant-speeds and connected in parallel. In order to separate oil from refrigerant discharged from the compressors 1a and 1b, a first oil separator 2a is connected to the outlet side of the first compressor 1a and a second oil separator 2b is connected to the outlet side of the second compressor 1b. The outlet sides of the first and second oil separators 2a and 2b are merged together and then connected to first and second condensers 6a and 6b through a four-way valve 5. The first and second condensers 6a and 6b are connected to an indoor unit (not shown) through a liquid receiver 8. A first condenser fan 7a is situated in the vicinity of the first condenser 6a and a second condenser fan 7b is situated in the vicinity of the second condenser 6b. The refrigerant-return side of the indoor unit is connected to the inlet sides of the first and second compressors 1a and 1b through an accumulator 9.
A pressure-equalizing pipe 3 for equalizing the pressures of the refrigerant of the first and second compressors 1a and 1b and an oil-equalizing pipe 4 for equalizing the quantities of the oil of the first and second compressors 1a and 1b are each provided to connect the first and second compressors 1a and 1b. 
A conventional method for controlling the conventional outdoor unit of the conventional air conditioner is described hereunder.
FIG. 2 is a flow chart showing the operation of the conventional outdoor unit of the conventional air conditioner.
In the operation of the conventional outdoor unit, when an increase of the total capacity of the outdoor unit is required according to a capacity-increase command while one compressor is being operated and the other compressor is being stopped(S10), the compressor being currently operated is stopped and made to wait for a predetermined time period (S20) to reduce a pressure difference between the compressor being operated and the other compressor being stopped. When it is determined that the predetermined time period has elapsed (S30), the two compressors are started at the same time (S40).
In the conventional outdoor unit operated as described above, when one compressor is intended to be started while the other compressor is being operated, there is a great concern that the compressor will not start due to the large pressure difference between its inlet and outlet sides.
Accordingly, in this case, it is necessary to reduce the pressure difference between the inlet and outlet sides of the compressor intended to start.
As described above, when the total capacity of the air conditioner should be increased while one of two compressors is being operated, the compressor being operated should be stopped before the other compressor is operated. Accordingly, the cooling or heating operation of the air conditioner is stopped for the predetermined time period, so that there occurs a problem that the comfort of a user is decreased by the stoppage of air conditioning.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an air conditioner with a pressure regulation device and method for controlling the same, which is capable of starting one or more additional compressors without hindrance when it is necessary to start the additional compressors according to an increase capacity thereof.
In order to accomplish the above object, the present invention provides an air conditioner with pressure regulation device, the air conditioner controlling the number of operated compressors according to load, comprising: a bypass conduit for guiding gaseous refrigerant from the outlet side of compressor to the inlet side of the compressor; a bypass valve arranged on the bypass conduit for selectively opening and shutting the bypass conduit; and a control unit for controlling the opening and closing of the bypass valve so as to assist of the compressor in stop.
In addition, the present invention provides a method for controlling an air conditioner, the air conditioner being comprised of a bypass conduit for guiding gaseous refrigerant from the outlet side of compressor to the inlet side of the compressor; a bypass valve arranged on the bypass conduit for selectively opening and shutting the bypass conduit; and a control unit for controlling the opening and closing of the bypass valve so as to assist of the compressor in stop, a plurality of compressors operated according to load, a plurality of bypass conduits for guiding gaseous refrigerant from the outlet sides of the compressors to the inlet sides of the compressors, and a pressure regulation unit consisting of a first valve disposed between the inlet side of the compressor and a refrigerant conduit connected to the return side of the indoor unit of the air conditioner, a capillary tube connected in parallel with the first valve and a second valve connected in serial with the capillary tube to be selectively opened and closed, comprising the steps of: opening the bypass valves for one or more compressors to be started, and closing all the valves of the pressure regulation units for one or more compressors to be started; starting the compressors and reducing the pressure difference between the interior and exterior of each of the compressors stage by stage by controlling the opening of the pressure regulation units; and shutting the bypass conduits and normally driving the compressors.